<template>
  <div class="s-canvas" @click="createdCode">
    <canvas ref="sCanvas" :width="contentWidth" :height="contentHeight"></canvas>
  </div>
</template>
<script>
import Vue from 'vue';

export default Vue.extend({
  props: {
    fontSizeMin: {
      type: Number,
      default: 25,
    },
    fontSizeMax: {
      type: Number,
      default: 30,
    },
    backgroundColorMin: {
      type: Number,
      default: 255,
    },
    backgroundColorMax: {
      type: Number,
      default: 255,
    },
    colorMin: {
      type: Number,
      default: 0,
    },
    colorMax: {
      type: Number,
      default: 160,
    },
    lineColorMin: {
      type: Number,
      default: 100,
    },
    lineColorMax: {
      type: Number,
      default: 255,
    },
    dotColorMin: {
      type: Number,
      default: 0,
    },
    dotColorMax: {
      type: Number,
      default: 255,
    },
    contentWidth: {
      type: Number,
      default: 120,
    },
    contentHeight: {
      type: Number,
      default: 34,
    },
  },
  data() {
    return {
      identifyCode: '',
    };
  },
  mounted() {
    this.createdCode();
  },
  methods: {
    // 生成4个随机数
    getCode() {
      this.$emit('getCode', this.identifyCode);
    },
    createdCode() {
      const len = 4;
      const codeList = [];
      const chars = 'ABCDEFGHJKMNPQRSTWXYZabcdefhijkmnprstwxyz0123456789';
      const charsLen = chars.length;
      for (let i = 0; i < len; i++) {
        codeList.push(chars.charAt(Math.floor(Math.random() * charsLen)));
      }
      this.identifyCode = codeList.join('');
      this.$emit('getIdentifyCode', this.identifyCode.toLowerCase());
      this.drawPic();
    },

    // 生成一个随机数
    randomNum(min, max) {
      return Math.floor(Math.random() * (max - min) + min);
    },
    // 生成一个随机的颜色
    randomColor(min, max) {
      const r = this.randomNum(min, max);
      const g = this.randomNum(min, max);
      const b = this.randomNum(min, max);
      return `rgb(${r},${g},${b})`;
    },

    drawPic() {
      const canvas = this.$refs.sCanvas;
      const ctx = canvas.getContext('2d');
      ctx.textBaseline = 'bottom';
      // 绘制背景
      ctx.fillStyle = this.randomColor(this.backgroundColorMin, this.backgroundColorMax);
      ctx.fillRect(0, 0, this.contentWidth, this.contentHeight);
      // 绘制文字
      for (let i = 0; i < this.identifyCode.length; i++) {
        this.drawText(ctx, this.identifyCode[i], i);
      }
      this.drawLine(ctx);
      this.drawDot(ctx);
    },

    drawText(ctx, txt, i) {
      ctx.fillStyle = this.randomColor(this.colorMin, this.colorMax);
      ctx.font = `${this.randomNum(this.fontSizeMin, this.fontSizeMax)}px SimHei`;
      const x = (i + 1) * (this.contentWidth / (this.identifyCode.length + 1));
      const y = this.randomNum(this.fontSizeMax, this.contentHeight - 5);
      const deg = this.randomNum(-45, 45);
      // 修改坐标原点和旋转角度
      ctx.translate(x, y);
      ctx.rotate(deg * Math.PI / 180);
      ctx.fillText(txt, 0, 0);
      // 恢复坐标原点和旋转角度
      ctx.rotate(-deg * Math.PI / 180);
      ctx.translate(-x, -y);
    },

    // 绘制干扰线
    drawLine(ctx) {
      for (let i = 0; i < 5; i++) {
        ctx.strokeStyle = this.randomColor(this.lineColorMin, this.lineColorMax);
        ctx.beginPath();
        ctx.moveTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
        ctx.lineTo(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight));
        ctx.stroke();
      }
    },

    // 绘制干扰点
    drawDot(ctx) {
      for (let i = 0; i < 80; i++) {
        ctx.fillStyle = this.randomColor(0, 255);
        ctx.beginPath();
        ctx.arc(this.randomNum(0, this.contentWidth), this.randomNum(0, this.contentHeight), 1, 0, 2 * Math.PI);
        ctx.fill();
      }
    },
  },
});
</script>
<style scoped>
.s-canvas {
  height: 38px;
  cursor: pointer;
}
.s-canvas canvas{
  margin-top: 1px;
  margin-left: 8px;
}
</style>
